Rescuers forced to leave whales to the mercy of the tide

Volunteers and conservation workers were last night trying to keep alive 116 pilot whales - beached near Farewell Spit at the top of the South Island - long enough for high tide to rescue them.

Ten whales had already died as darkness fell despite the efforts of about 100 volunteers and 20 Department of Conservation staff to keep the pod cool and comfortable.

"We're trying to get them through to 2am [today], which is when the next high tide is, when we hope as many as possible can float off," DoC Golden Bay manager John Mason said.

The helpers yesterday covered the 4m- to 5m-long whales in wet sheets and set up pumps for sprinkler systems to keep them cool after they became stranded at 2pm on the beach at Puponga, Golden Bay.

But the whales faced several hours overnight without assistance as the helpers were moved off the beach about 8.30pm.

"It is too dangerous to leave people in the sea with whales a long way from shore with an incoming tide," Mr Mason said.

"It's unfortunate high tide is in the middle of the night and we'll be relying on them using their own abilities to refloat themselves. I think most will survive until high tide."

Based on previous experience, he predicted that about 30 per cent would refloat themselves.

DoC staff had felt the whales were in trouble since seeing them close to the shore about midday yesterday.

"They looked quite confused and were quite close to shore, so it was no surprise to us when they started to strand on the falling tide," Mr Mason said.

"We were actually standing in the sea, forming a barrier between the whales and the beach and gently moving them out. Twice they went out to 200m from the shore, but both times they came back in."

Mr Mason was grateful to the volunteers. "A stranding of this size, there's no way we [DoC] can deal with it by ourselves.

"Nobody really knows why whales get stranded. This is a well-known spot for stranding and it has happened many times in the past five years."

The last stranding of yesterday's size was in 1998.

Mr Mason said DoC would conduct a search of the shoreline early this morning before deciding what more its staff and the volunteers could do.